Real estate agents often suggest that their clients bake bread or cookies just before an open house to create a warm and inviting aroma. But as an ongoing quality-control issue concerning Owens Corning (OC) fiberglass batts demonstrates, the aroma of baked goods can be a problem when it’s coming from the insulation.

Bio-based binder. A little more than two years ago, OC reformulated its familiar pink fiberglass batts by replacing a formaldehyde-based binder with a “greener” material containing no formaldehyde. While the performance of the reformulated batts — dubbed EcoTouch by the manufacturer — was unchanged, installers quickly noticed a minor side effect of the new binder: When removed from their plastic wrapping, the batts smelled distinctly of what’s been described as caramel or cooked sugar.

OC declines to say exactly what’s in the formaldehyde-free binder, beyond describing it as a “bio-based material.” Some nice sleuthing by Martin Holladay at the Green Building Advisor site (greenbuildingadvisor.com), however, suggests that a key ingredient may be maltodextrin, a corn-derived substance found in many processed foods and beverages.

In any event, the company took the precaution of circulating a letter explaining the new aroma to contractors and consumers early in 2011.

“The use of natural ingredients can sometimes cause different scents when installing the product,” the letter read in part. “This scent is very similar to the smell of baked goods. This scent is normal for bio-based materials, and will dissipate after a few days.”

“I kinda like it.” To the extent that anyone noticed the new smell at first, the reaction seems to have been mostly positive — not surprisingly, given that the old formaldehyde-based binder had a characteristic smell of its own, which reminded many installers of cat pee.

In what was likely a typical reaction in the weeks following the EcoTouch rollout, an August 2011 posting on the Contractor Talk website from an insulation contractor identifying himself as “Parts” asked if anyone knew when OC batts acquired their new smell. “Instead of the old cat smell,” he noted, “it smelled ... like a burnt caramel.”

Following up on his initial post a few days later — after noting that he’d since been asked about the odor by two other contractors and one homeowner — Parts pronounced himself satisfied. “I kinda like the new smell of it, myself,” he wrote.

Covering the costs. But sometime in the past year or so, occasional shipments of EcoTouch batts have given off a much stronger and more persistent burned smell, which doesn’t dissipate even after weeks of post-installation exposure to air. In what was apparently a response to customer complaints, OC recently began sending contractors an updated version of its 2011 explanatory letter, which is identical to the original except for an additional closing paragraph.

“As always,” the added text reads in part, “Owens Corning stands behind its products and will cover the cost of replacing any products that do not meet customer needs. Please do not hesitate to contact your local Owens Corning Area Sales Manager if you have any concerns.”

According to an unnamed OC spokesperson who agreed to respond to JLC’s questions by email, the company has so far received a total of 31 odor-related complaints. The stronger odors seem to originate during manufacturing, when inconsistencies in the thermal curing of the binder may allow some batts to become “overbaked.” (Because it contains no binder, loose-fill fiberglass is not affected.)

“The cure cycle has always been a critical component of how well insulation performs and how it smells,” the spokesperson wrote. “We are implementing improved cure control systems to assist manufacturing personnel in properly curing EcoTouch insulation and eliminating instances of odor ... and, in fact, we have measured reduced instances of over cure situations.”

OC declined to answer questions about the feasibility of pulling out overbaked batts at the manufacturing end before they enter the supply stream, or about how many defective products it has so far paid to replace. But the encouraging news for contractors who use OC batts is that the odor problem seems to be limited in scope, and the company is making good on its promise to replace any defective material. — Jon Vara